php判断值是否为空实例代码

if( isset($_GET[’name’]) )//判断传来的值是否为空。 
{ 
       echo "值为空"; 
} 

$sql = "select * form abc"
$result = mysql_query($sql);
$row = mysql_fetch_array($result);
if(!$row)//开始判断是够为空
{
echo "null";
}
else
{
echo "not null";
}

$a = null;
$b = false;
if (is_null($a)) echo '$a 为NULL' . "";
if (is_null($b)) echo '$b 为NULL' . "";
if (is_null($c)) echo '$c 为NULL' . "";
// 显示结果为
// $a 为NULL
// Undefined variable: c

//array_filter() 将删除 $res 中所有等值为 FALSE 的条目
$filter_res = array_filter($res);

if(!empty($filter_res))
{
     //数组不为空的操作
}
else
{
    //数组为空的操作
}

<?php
//上面把你要判断的数组放在这，名字是$shuzu
foreach ($shuzu as $v1)  
{ 
foreach ($v1 as $v2)  
{ 
//print "$v2";
$shunzi =$shunzi.$v2;
}
if($shunzi=="")
{
echo "数组是空的";
}
else
{
echo "数组有元素";
}
?>

count($arr),size($arr);

$arr= array("");
echo count($arr);
echo size($arr);
//输出1

class Test{
public static function array_is_null($arr = null){
if(is_array($arr)){
foreach($arr as $k=>$v){
if($v&&!is_array($v)){
return false;
}
$t = self::array_is_null($v);
if(!$t){
return false;
}
}
return true;
}elseif(!$arr){
return true;
}else{
return false;
}
}
}

function get_keywords($html)
{
$html=strtolower($html);
preg_match("@<head[^>]*>(.*?)</head>@si",$html, $regs); 
$headdata = $regs[1];
preg_match("/<meta +name *=["']?keywords["']? *content=["']?([^<>"]+)["']?/i", $headdata, $res);
if (isset ($res)) {
$keywords = $res[1];
}
if ($keywords == "") $keywords = "无";
$keywords=replace_word(textcut($keywords,250));
$keywords=str_replace("-",",",$keywords);
$keywords=str_replace("，",",",$keywords);
$keywords=str_replace(" ",",",$keywords);
$keywords=str_replace("|",",",$keywords);
$keywords=str_replace("、",",",$keywords);
$keywords=str_replace(",,",",",$keywords);
$keywords=str_replace("<","",$keywords);
$keywords=str_replace(">","",$keywords);
return addslashes(trim($keywords));
}

function get_title($html)
{
  $html=strtolower($html);
 $title = str_replace(" - ",",",cut($html,"<title>", "</title>" ));
//if ($title == "") $title = "无标题";
if ($title) $title=replace_word(textcut($title,80));
if ($title) $title=preg_replace("/<(.*?)>/","",$title);
return addslashes(trim($title));
}

function get_description($html)
{
$html=strtolower($html);
preg_match("@<head[^>]*>(.*?)</head>@si",$html, $regs); 
$headdata = $regs[1];
preg_match("/<meta +name *=["']?description["']? *content=["']?([^<>"]+)["']?/i", $headdata, $res);
      if (isset ($res)) {
       $description = $res[1];
      }
if ($description == "") $description = "无";
$description=replace_word(textcut($description,250));
$description=str_replace("-",",",$description);
$description=str_replace("，",",",$description);
$description=str_replace(" ",",",$description);
$description=str_replace("|",",",$description);
$description=str_replace("、",",",$description);
$description=str_replace(",,",",",$description);
$description=str_replace("<","",$description);
$description=str_replace(">","",$description);
return addslashes(trim($description));
}

file_delete = "home/meeta/my.php";

if (unlink($file_delete)) {
echo "The file was deleted successfully.", "n";
} else {
echo "The specified file could not be deleted. Please try again.", "n";
}
?>

$myfile = "./test1.txt";
if (file_exists($myfile)) {
$result=unlink ($myfile);
echo $result;
}
?>

<?php
function del_dir($dir){    //删除目录
    if(!($mydir=@dir($dir))){
        return;
    }
    while($file=$mydir->read()){
        if(is_dir("$dir$file") && $file!='.' && $file!='..'){
            @chmod("$dir$file", 0777);
            del_dir("$dir$file");
        }elseif(is_file("$dir/$file")){
            $file_time=@stat($file);    //读取文件的最后更新时间
            if(time()-$file_time>3600*24*14){
                @chmod("$dir/$file", 0777);
                @unlink("$dir/$file");
            }
        }
    }
    $mydir->close();
    @chmod($dir, 0777);
    @rmdir($dir);
}
?>

<div style="page-break-after: always"><span style="display: none"> </span></div>

<div style="page-break-after: always"><span style="display: none"> </span></div> 

function pageBreak($content){ 
    $content  = $content; 
    $pattern  = "/<div style="page-break-after: always"><span style="display: none">  
</span></div>/"; 
    $strSplit = preg_split($pattern, $content, -1, PREG_SPLIT_NO_EMPTY); 
    $count    = count($strSplit); 
    $outStr   = ""; 
    $i        = 1; 
 
    if ($count > 1 ) { 
        $outStr   = "<div id='page_break'>"; 
        foreach($strSplit as $value) { 
            if ($i <= 1) { 
                $outStr .= "<div id='page_$i'>$value</div>"; 
            } else { 
                $outStr .= "<div id='page_$i' class='collapse'>$value</div>"; 
            } 
            $i++; 
        } 
 
        $outStr .= "<div class='num'>"; 
        for ($i = 1; $i <= $count; $i++) { 
            $outStr .= "<li>$i</li>"; 
        } 
        $outStr .= "</div></div>"; 
        return $outStr; 
    } else { 
        return $content; 
    } 
} 

#page_break {} 
#page_break .collapse {display: none;} 
#page_break .num {padding: 10px 0;text-align: center;} 
#page_break .num li{display: inline; margin: 0 2px;padding: 3px 5px;border:1px solid #abcee4; 
background-color: #fff;color: #369;text-align: center;cursor: pointer;overflow: hidden;} 
#page_break .num li.on{background-color: #369;color: #fff;font-weight: bold;}